The goal of this research will be to examine the relationships between cellular growth status and cell function in an effort to understand factors which contribute to collagen and proteoglycan accumulation in the development of diabetic pathologies. Cultured normal human skin fibroblasts will be studied in actively growing, low passaged (young) cultures, in quiescent (serum-restricted) sparse or confluent cultures, and in cultures near terminal phase (senescence). Collagen and proteoglycan synthesis by these cultures will be assessed by the incorporation of radioisotope from 14C-proline and from Na 35SO4 plus 3H-glucosamine, respectively, into macromolecules. Similar assessments would compare 14C-glucose incorporation into glycogen and proteoglycan. The extrinsic regulation of these processes by insulin and hydrocortisone will be of specific interest. The effects of these hormones would be studied in growth media supplemented with untreated fetal bovine serum or with serum stripped of hormones by treatment with charcoal and anti-insulin antibody. The involvement of cyclic AMP as a possible obligatory intrinsic regulator will be examined by studies of growth and macromolecule accumulation in the presence of prostaglandin E2 with or without the phosphodiesterase inhibitor, 1-methyl, 3-isobutylxanthine. Finally, properties of the various cultures will be examined under conditions which reflect metabolic derangements of diabetes mellitus. For these studies, cells would be grown or maintained in various concentrations of sera from normal and uncontrolled, spontaneously diabetic rats. Other specific conditions examined would include elevated levels of glucose, ketone bodies, urea and growth hormone.